[0035] Example: A method for controlling generator frequency using prime mover output torque. Taking IEEE's 3 machines and 9 nodes as a simulation case, the system is required to quickly converge to 50Hz when the system suddenly increases by 50MW at t=1.5s. At the same time, the maximum frequency deviation does not exceed 0.02Hz.
[0036] According to the raw data of the IEEE 3-machine and 9-node model, data such as line parameters, transformer parameters, load parameters and generator parameters are analyzed and calculated.
[0037] Such as figure 1 As shown, the control method of the present invention is implemented through the following steps:
[0038] A: Calculate the rated power P of each unit Gi Set the power adjustment range of each unit, and determine the load adjustment effect coefficient K of the grid load LD The numerical value.
[0039] Under the rated operation of the system, calculate the rated power value P of 3 units respectively G1 , P G2 , P G3 , Set the respective power adjustment ranges of the 3 units; and determine the load adjustment effect coefficient K of the grid load LD The numerical value.
[0040] B: Calculate the disturbance ΔP of each unit i.
[0041] First calculate the real-time output power P of the 3 units separately G1 ', P G2 ', P G3 ';
[0042] Combined with the rated power value P of 3 units G1 , P G2 , P G3 , Calculate the change ΔP of the total output power of the unit.
[0043] ΔP = X i = 1 n P Gi ′ - X i = 1 n P Gi - - - ( 1 )
[0044] Then the rated output power of the 3 units P Gi And the change ΔP of the sum of the output power of the units, respectively, into equation (2) to obtain the disturbance ΔP of the three units 1 , ΔP 2 , ΔP 3.
[0045] ΔP i = P Gi X i = 1 n P Gi X ΔP - - - ( 2 )
[0046] Among them, n is the total number of units, P Gi 'Is the real-time output power of the i-th unit, P Gi Is the rated power of the i-th unit, ΔP i Is the disturbance of the i-th unit.
[0047] C: Calculate the unit adjusted power K of each unit Gi.
[0048] The real-time output power P of 3 units G1 ', P G2 ', P G3 'And the rated frequency f of the system N , Respectively put into equation (3), calculate the unit regulated power K of 3 units G1 , K G2 , K G3.
[0049] K Gi = P Gi ′ f N X K Gi * - - - ( 3 )
[0050] Where K Gi Regulate the unit power value for the i-th unit, K Gi * K Gi The standard unit value of, generally takes 16.7-25; in order to meet the actual output capacity of the unit, K Gi Make a limit,
[0051] K Gi (min)≤K Gi ≤K Gi (max) (4)
[0052] Where K Gi (min) and K Gi (max) are the lower limit and upper limit of the unit regulated power of the i-th unit. When K Gi Less than K Gi (min), take K Gi =K Gi (min); When K Gi Greater than K Gi (max), take K Gi =K Gi (max).
[0053] In this embodiment, K G1 * = 20, K G2 * = 25, K G3 * = 17, K G1 (min) = 0.034, K G1 (max) = 0.051; K G2 (min) = 0.065, K G2 (max)=0.098; K G3 (min) = 0.023, K G3 (max)=0.035.
[0054] D: According to the real-time frequency f and rated frequency f of the system N The difference Δf of each unit is performed on the PI calculation of each unit to obtain the power adjustment ΔP of each unit Gi , Considering the regulation effect of electric load, we get
[0055] (ΔP Gi -ΔP i )÷K LD =Δf (5)
[0056] The real-time frequency f of the system and the rated frequency f N The difference Δf is performed on the three units separately to calculate the power adjustment ΔP of the three units G1 , ΔP G2 , ΔP G3.
[0057] Among them, the proportional operation P is equivalent to the primary frequency modulation of the power system, and the proportional coefficients of the 3 units are respectively taken as K G1 , K G2 , K G3. The integral operation I is equivalent to the second frequency modulation of the power system, and the integral coefficient of all units is 0.01.
[0058] Adjust the power adjustment ΔP of 3 units G1 , ΔP G2 , ΔP G3 And the disturbance ΔP of 3 units 1 , ΔP 2 , ΔP 3 , Respectively bring them into formula (5).
[0059] E: According to the rotor motion equation of each unit, combined with the formula (5) obtained in step D to obtain the real-time output torque T of the prime mover of each unit Mi , Will calculate T Mi As the input of each unit to control the output frequency of the system.
[0060] The rotor motion equation of each unit is as follows:
[0061] 1 ΔT i ( S ) = 1 T Ji S + D i X 1 Δf ( S ) X 1 2 π ΔT i = ΔT Mi - ΔT Ei ΔT Mi = T Mi - T MNi ΔT Ei = P Ei ω i - P ENi ω Ni - - - ( 6 )
[0062] Where T Ji Is the inertial time constant of the i-th unit; D i Is the damping coefficient of the i-th unit; ω i Is the real-time angular velocity of the i-th unit, ω Ni Is the rated angular velocity of the i-th unit; T Mi Real-time output mechanical torque for the prime mover of the i-th unit, T MNi Is the rated output mechanical torque of the prime mover of the i-th unit; P Ei Is the real-time electromagnetic power of the i-th unit, P ENi Is the rated electromagnetic power of the i-th unit; ΔT Ei Is the change of electromagnetic torque of the i-th unit; ΔT Mi Is the change in the mechanical torque of the prime mover of the i-th unit; ΔT i It is the difference between the change in the mechanical torque of the prime mover of the i-th unit and the change in the electromagnetic torque of the i-th unit.
[0063] In accordance with the actual project, ignoring losses such as damping friction, the real-time electromagnetic power P Ei Take the real-time output power P of the i-th unit Gi ', the rated electromagnetic power P of the i-th unit ENi Take the rated output power P of the i-th unit Gi , The prime mover rated output mechanical torque T of the i-th unit MNi Take as the rated output torque of the i-th unit
[0064] Substituting the respective difference Δf of the three units in step D into equation (6), the real-time output mechanical torque T of the prime mover of the three units is calculated M1 , T M2 , T M3. Where T M1 , T M2 , T M3 It is a function of the real-time frequency f of the system.
[0065] The calculated prime movers of the 3 units output mechanical torque T in real time M1 , T M2 , T M3 , Respectively as the input of 3 units to control the real-time frequency f of the system.
[0066] The simulated system output frequency diagram of the present invention, such as figure 2 Shown.
